Compared with the liquid crystal display device in the conventional technology, the organic light emitting diode (OLED) display device has the characteristics of fast response, excellent color purity and brightness, high contrast, wide viewing angle, and the like.
Generally, the OLED display devices can be classified into passive matrix OLED (PMOLED) display devices and active matrix OLED (AMOLED) display devices according to driving methods thereof.
The structure and driving method of the PMOLED display device are relatively simple, which makes the PMOLED display device easy to be manufactured, but the PMOLED's resolution and size are limited. Therefore, the PMOLED display devices are generally relatively small and are often used to display characters and small icons.
The AMOLED is driven by a thin film transistor (TFT) including a storage capacitor, so that a large-sized and high-resolution display panel can be realized. The AMOLED display devices can be made much larger than the PMOLED display devices and are not limited by size and resolution. Therefore, the AMOLED display devices are considered to be the development direction of future display technologies.
For the AMOLED display device, currents flowing through the OLED at different time for the same image data voltage are different due to factors such as instability of the driving transistor and aging of the OLED, resulting in uneven display brightness of the entire display panel. These problems are difficult to completely be overcome in the process, so they are solved by various compensation techniques.
The compensation method can be divided into internal compensation and external compensation. The internal compensation refers to a compensation method through a sub-circuit built by using thin-film transistors inside a pixel. The external compensation refers to a method of sensing electrical or optical characteristics of a pixel through an external driving circuit or device and then performing compensation. Generally, the compensation range of the internal compensation is too small to cover the characteristic change of the transistor. Although the compensation range of the external compensation is wide, it is easy to generate a compensation mura, and the compensation timeliness is poor.
It should be noted that the information disclosed in the foregoing background section is only for enhancement of understanding of the background of the present disclosure and therefore may include information that does not constitute the prior art that is already known to those of ordinary skill in the art.